This is a project to study the genetics of Inflammatory Bowel Disease (IBD) in collaboration with Drs. Steven Brant and Theodore Bayliss of Johns Hopkins University School of Medicine and with the International IBD Consortium. An international consortium of investigators who have previously published genome wide linkage screens for IBD was formed and all members agreed to genotype the same markers in two candidate regions on at least 50 highly families with both parents and two or more affected children available for genotyping. These data were then deposited into a common database at the University of Canberra, anonymized and then distributed to the participating groups. Each group performed its own analyses of these data and presented them at a workshop in Australia in September. Additional genotyping was performed in this fiscal year and a paper was published in the American Journal of Human Genetics that strongly confirmed evidence of one susceptibility locus on chromosome 16 but failed to confirm a second locus on chromosome 12. These analyses led directly to the recentl cloning (by two independent members of the consortium) of a gene on chromosome 16 that increases risk for IBD in some families. Dr. Bailey-Wilson is head of the Analysis committee for this consortium and will continue to interact with Drs. Brant, Bayliss and the IBD Consortium on future analyses of the genetics of IBD. Dr. Bailey-Wilson also is collaborating with Drs. Brant and Bayliss and Dr. Carolien Panhuysen on analyses of Dr. Brant's IBD data. Linkage and association studies of genome-wide scan and fine mapping data are ongoing.